Reproduction steps: 1. Go to www.google.com/mail/ Crash! This appears to be JSC issue because it doesn't reproduce on Chromium.
Can we get a crashtrace and platform?
Stack trace: Thread 0 Crashed: Dispatch queue: com.apple.main-thread 0 com.apple.JavaScriptCore 0x00000001007daec5 JSC::DFG::JITCompiler::jumpFromSpeculativeToNonSpeculative(JSC::DFG::SpeculationCheck const&, JSC::DFG::EntryLocation const&, JSC::DFG::SpeculationRecovery*, JSC::DFG::NodeToRegisterMap&, JSC::DFG::NodeToRegisterMap&) + 5909 1 com.apple.JavaScriptCore 0x00000001007dc25a JSC::DFG::JITCompiler::linkSpeculationChecks(JSC::DFG::SpeculativeJIT&, JSC::DFG::NonSpeculativeJIT&) + 282 2 com.apple.JavaScriptCore 0x00000001007dcc87 JSC::DFG::JITCompiler::compileBody() + 2359 3 com.apple.JavaScriptCore 0x00000001007ddf04 JSC::DFG::JITCompiler::compileFunction(JSC::JITCode&, JSC::MacroAssemblerCodePtr&) + 788 4 com.apple.JavaScriptCore 0x0000000100817241 JSC::FunctionExecutable::compileForCallInternal(JSC::ExecState*, JSC::ScopeChainNode*, JSC::ExecState*) + 2193 5 com.apple.JavaScriptCore 0x00000001008324db JSC::Interpreter::prepareForRepeatCall(JSC::FunctionExecutable*, JSC::ExecState*, JSC::JSFunction*, int, JSC::ScopeChainNode*) + 523 6 com.apple.JavaScriptCore 0x000000010078a1af JSC::arrayProtoFuncForEach(JSC::ExecState*) + 2831 7 ??? 0x00003b3019e011e8 0 + 65077778584040 8 com.apple.JavaScriptCore 0x0000000100831245 JSC::Interpreter::execute(JSC::ProgramExecutable*, JSC::ExecState*, JSC::ScopeChainNode*, JSC::JSObject*) + 1573 9 ??? 0x0000000106f357a0 0 + 4411578272
<rdar://problem/9931900>
(In reply to comment #1) > Can we get a crashtrace and platform? Snow Leopard on MacPro.
Created attachment 103545 [details] the patch
*** Bug 66011 has been marked as a duplicate of this bug. ***
Comment on attachment 103545 [details] the patch Clearing flags on attachment: 103545 Committed r92804: <http://trac.webkit.org/changeset/92804>
All reviewed patches have been landed. Closing bug.
*** Bug 66115 has been marked as a duplicate of this bug. ***
Is it not possible to write an automated regression test for this?
Seems like it should be possible. If possible, all checkins should come with a regression test.
(In reply to comment #10) > Is it not possible to write an automated regression test for this? Sorry for not noting this in the ChangeLog, but there is no obvious automated regression test. The bug arises out of misuse of a hidden "this" argument to constructor calls. This is a synthetic notion introduced in our bytecode and our JITs - it is not exposed in the JavaScript language. As well, the bug only happens when three different register allocators in the system (the bytecompiler's virtual register allocator, the DFG parser's virtual register allocator, and the DFG back-end's physical register allocator) all make exactly the "wrong" decision based on the input. A test that would cause a failure just before this fix landed would be unlikely to continue to cause failures if even slight changes in register allocation were made subsequently.